class_docstr: Base class for estimators
  
  Ensure proper initialization of Mixins.
code: def data(self):
      return self._backend.data
  
imports: from ..parallel import Layer, make_group
  from ..parallel.base import ParamMixin
  from ..parallel.wrapper import EstimatorMixin
  from ..parallel._base_functions import check_stack
  from ..externals.sklearn.base import BaseEstimator
  from ..externals.sklearn.base import clone
label_desc: Use image node_id 3 for calling the BaseEstimator obj's underlying member method code with example usage: obj.data() and returns: self